Born in 1962 in a Japan beginning a decades-long manufacturing boom, Shinya Yamanaka was the only son of a factory owner who produced parts for sewing machines.

But even as the country's industries exploded in the 1970s, his father told him he should not follow the traditional Japanese path and take over the family business, but become a doctor.

Half a century later and after a stint as an orthopaedic surgeon, he is a leading authority on how cells work.

Kyoto University-based Yamanaka was being celebrated Monday for his work, alongside Briton John Gurdon, on how cells can be reprogrammed.

So-called "nuclear reprogramming" uses a fully-developed adult cell to create a stem cell -- a kind of blank slate that has the potential to become any other kind of cell in the body.

Scientists say in this way they can generate materials either to experiment on, or to use within the body -- perhaps as a means of repairing or even replacing damaged or diseased organs.

Gurdon's work proved that mature cells maintain the "memory" of what they could have been; a brain cell that specialises in transmitting messages retains its ability to absorb nutrients like a cell in the wall of the intestine.

To do this, he took the nucleus from a specialised cell and implanted it into an egg without a nucleus. Allowed to develop naturally, this becomes an early-stage embryo containing stem cells.

Harvesting those cells necessitates the destruction of that embryo.

Yamanaka got fully developed adult cells to create stem cells without the need for an embryo to be created -- or destroyed.

Writing in the journal Nature in 2010, Yamanaka explained his work.

"The stable states of differentiated cells are now known to be controlled by dynamic mechanisms that can easily be perturbed.

"An adult cell can therefore be reprogrammed, altering its pattern of gene expression, and hence its fate, to that typical of another cell type."

Yamanaka called his discovery "induced pluripotent stem (iPS) cells".

His work was hailed as a breakthrough because it demonstrated that it was possible to sidestep the sticky ethical issue of embryonic stem cell research.

Despite its huge promise, many balked at the idea of using -- destroying -- an embryo to get the important stem cells.

It was less of a problem in animal experiments but became a huge hurdle when moving to work on human cells. Religious conservatives, amongst others, objected and stem cell research was stymied.

"If embryo stem cell research is the only way to help patients, then I think that is what we should do," Yamanaka once said.

"At the same time... as a natural feeling, I do want to avoid the usage of human embryos... Human embryos are not like skin cells, they can be babies if transplanted. That is why we are doing what we are doing" with iPS cells.

Stem cell research is seen as having the potential to save lives by helping to find cures for diseases such as cancer and diabetes or to replace damaged cells, tissues and organs.

It also has been touted as a promising intervention for neurodegenerative diseases such as Parkinson's or Alzheimer's, as well as helping create new drugs and improving research.

Yamanaka is acutely aware of how controversial his science can be and says it needs to be strictly regulated.

"We should limit the application of technology to treatment or what can make patients happier," he has said. "We may be able to generate new life (with this technique), so we are presented with another ethical issue."

He draws the line at creating a new life simply to grow new organs, theoretically possible using his technique.

"It is technically very difficult (but) organ shortage is a big problem right now in many countries. We need some kind of regulation," he has said.

Yamanaka was recognised in 2009, alongside Gurdon, with the Lasker Prize for stem cell research. This year he shared the 1.2-million-euro Millennium Technology Prize with a software engineer.